1. Field of the Invention
The present invention is related to the field of navigational instruments, and in particular, to the electronic display of navigational information for aircraft.
2. Description of Related Art
A pilot's awareness of her aircraft and its relationship to the surrounding environment is a large factor in ensuring safe flight. Originally, such information was provided by the pilot's own visual, tactile and other senses. Eventually, various devices were developed to augment the pilot's senses including compasses to determine direction, altimeters to measure altitude and Pitot tubes to determine airspeed velocity. Another example includes radar that uses radio signals to accurately indicate the location of the pilot's aircraft, ground contours and other aircraft.
Generally, more, and more accurate, information about the location and movement of the aircraft with respect to obstacles is a boon to aviation safety. As a result, navigational devices have been, and continue to be, the subject of ongoing development efforts. However, so much navigational information is now available from navigational devices that not all of the information can be effectively processed by the pilot. Therefore, presenting the information in a clear and useable manner, in addition to its volume and accuracy, has also become an important factor. Initially, presentation of the navigational information consisted of careful arrangement of various mechanical gauges, but the amount of information presented by gauges is limited due to the physical size of the gauges and the limited space on the flight deck. More recently, electronic displays have provided an alternative to gauges by allowing variation of the information presented to the pilot—typically in response to the pilot's commands.
For example, U.S. Pat. No. 6,122,141 to Briffe et al. (Briffe) discloses an aircraft navigational system. As shown in FIG. 1 of Briffe, the navigational system includes four display screens that are positioned side-by-side. The middle two display screens 18, 20 are Multi-Function Displays (MFD's) that operate independently, and that are configured to display any of a long list of aeronautical displays. Examples of the MFD displays include: (1) a horizontal situation and vertical profile screen; (2) an approach chart; (3) a GCAS display (terrain avoidance); and (4) an airport chart that graphically displays the current position of the Own ship aircraft, as shown in FIG. 9 of Briffe.
The MFD's are set up to have redundant functionality. This allows a pilot and a co-pilot to, for example, work on the same display at the same time on separate screens. In one particular example discussed in Briffe, one pilot may work on a high-altitude chart displayed on the first MFD while another pilot is working on the same high-altitude chart displayed on the second MFD. This may be useful when two pilots wish to view a particular display in different range-scales or formats.
The two, side-by-side MFD's are also configured to allow pilots to “cross-over” between the MFD's by moving a cursor on one MFD at a high rate of speed toward the other MFD. The ability to cross-over allows the user to work on either of the MFD's. Each individual MFD can be further configured to operate in a split-screen format to display up to six different display windows on one display screen, as shown in FIG. 14 of Briffe. Despite such improvements in the amount, accuracy and presentation of navigational information, additional improvements are always desirable due to the importance of safe air travel.
Therefore, it would be advantageous to have additional navigational information that improves aircraft safety. It would be further advantageous if such navigational information were presented in a clear and useful manner to the pilot.